I hadn't heard about the ARM Thinkpad, that's very interesting. For me the reason ARM on the Framework is an exciting possibility is that you can switch out the mainboard with the processor. The X13s is $1,300 which is quite the investment into such an early platform. With a framework laptop, you could have an ARM mainboard, but with the ability to switch it out with an x86-64 mainboard without having to invest in a whole new laptop. It could also go the other way, having a laptop on hand and wanting to dive into ARM, you would just have to buy an ARM mainboard instead of an entire laptop.

Arm on linux works pretty well.